The present invention relates to a locking mechanism for securing an articulating shaft member to a surface. In particular, the present invention relates to a locking mechanism for mounting to the underside of a table to lock a table leg in either an extended position or folded position. Preferably, there are at least two table legs attached to a table by the inventive locking mechanisms.
Various prior art locking mechanisms have been applied to the underside of tables to hold table legs in upright or folded positions. For example, Pfister U.S. Pat. No. 5,845,589 and Pfister U.S. Pat. No. 5,673,633 both disclose folding table leg systems for locking and unlocking a table leg in a upright or folded position. In each patent a biased lever controls the locking and unlocking of the table leg. In the Pfister patents, the operator pushes on the lever, releasing a latch member from a locked groove to allow manipulation of the table leg. The push lever system of the prior art creates the possibility for an accidental pushing of the operative lever by a knee or leg, thereby causing the table leg to be released from its locked upright position and become folded. In addition, the Paster patent designs are complex, requiring many parts and components.
The present invention is adaptable for mounting to any surface and for locking any member in a upright or folded position relative to that surface. The present invention is a locking device for articulately mounting a shaft member to a support surface. In a preferred embodiment, the support surface is the underside of a table and the shaft member is a table leg. The locking device comprises a housing for mounting to the support surface, with the housing having a cavity therein, and the cavity having an opening therein. A shaft member support is rotatably mounted within the cavity between a first upright position and a second folded position. The shaft member support has a corresponding first lock groove to lock the shaft member support in the first upright position and a second lock grooves to lock the shaft member support in the second folded position. A latch member, located between the support surface and the shaft member support, is rotatably mounted within the housing cavity. The latch member has a finger thereon to selectively project into either the first or second lock groove of the shaft member support to define the position of the shaft member support relative to the housing.
In a preferred embodiment, the locking and unlocking of the shaft member support is controlled by a latch actuator located on the housing. When the latch actuator is pulled, the pulling motion translates movement over a cable to pull the latch member against a spring force away from the shaft member support, thereby removing the finger from a lock groove. With the latch actuator pulled and the finger removed from a lock groove, the shaft member support is free to rotate between its first upright and second folded positions. Once the shaft member support is in either its first upright position or its second folded position, the latch actuator is released allowing the spring force to urge the latch member toward the shaft member support. The movement of the latch member toward the shaft member support selectively inserts the finger on the latch member into either the first grove or the second lock groove, thereby locking the shaft member support in position relative to the housing.